List of properties that can be specified in <ProjectReference Properties=""> is undocumented

**Issue description**

This came out of an SDK support case. The list of properties that can be set in ProjectReference is undocumented. This list is not the same as the list in https://docs.microsoft.com/en-us/dotnet/core/project-sdk/msbuild-props or that document is incomplete (can't tell which). The list is also not the same as the list of all properties referenced in Microsoft.NET.Sdk.targets as at least one property referenced in there can't be set by Properties=.

In my view of these, I expect these to correspond to command line arguments to `dotnet build`, `dotnet pack`, or `dotnet publish`.

At least the following properties are missing documentation or have incomplete documentation:

* RuntimeIdentifier: sets the runtime identifier to build the target project for and reference as. Accepts empty string or `$(RuntimeIdentifier)` ; not clear how this interacts with `` property group item (note plural)
* SelfContained: accepts true or false to set the value of self-contained.

The list is semicolon separated; the existing document is so bad I had to probe for that!

**Target framework**

- [X] .NET Core (only tried 6.0)
- [ ] .NET Framework
- [ ] .NET Standard

```console
c>dotnet --version
6.0.300
```